The 40 mm M320 grenade launcher has been fielded and is expected to replace the M203 launcher. The M320 allows for use of the new family of 40 mm low velocity ammunition described herein, developed to meet new user needs. It is desired to launch projectile(s) from conventional battlefield M203 or M320 grenade launcher(s) but with a lack of projectile spinning that will then make it possible to further install camera/guidance equipment at the front of the projectile that would ordinarily not function on a rapidly spinning projectile. An M203 or M320 grenade launcher however has internal rifling which always would engage and spin up such a projectile during launch. This ammunition round will allow a projectile to be launched from a conventional battlefield M203 or M320 grenade launcher, but with a lack of projectile spinning. This is not otherwise possible, conventionally.
A feature of this ammunition round is a joint area with an obturator means that is free to spin. This can spin decouple the projectile from the rifling action of the launcher. Then, the parts of the ammunition round that the M203 or M320 grenade launcher's internal rifling can engage and spin up are only on such obturator means. Because the projectile is of a smaller diameter than the obturator means, the projectile cannot be engaged or be spun up by the M203 or M320 grenade launcher's internal rifling. Even if the obturator means were to be spun up by the M203 or M320 grenade launcher's internal rifling yet the actual projectile would not be spun up. This is what is sought. This lack of projectile spinning makes it possible to further install camera/guidance equipment in the front of the projectile which would ordinarily not function on a rapidly spinning projectile. That added camera/guidance equipment could then further convert a regular 40 mm projectile into a smart, very accurate long distance projectile, and the camera/guidance equipment could certainly now be employed as is desired.
Another feature of particular note is a new ammunition round that can be launched with varying degrees of spin rate as well as with no spin at all, from the M320 by canting of rear fins on the projectile. The slowed down rate of spin also can make possible the use of frontal guidance and cameras ordinarily not possible with a rapidly spinning round which would ordinarily be the case when launched from an M320 due to internal rifling in the M320. So, this new ammunition round has a unique combination of slipping obturator ring(s) and also fins which can also be selectively canted at desired angles for low selectable spin rates.